1 Integrity concepts for future maritime Ground Based Augmentation Systems

Global Navigation Satellite Systems (GNSS) require augmentation to achieve integrity and accuracy performance for high-precise safety of life applications. The current standard maritime GNSS augmentation system is a differential GPS (DGPS) beacon system, which provides correction data and integrity information according to the IALA-standard [IALA-R-121]. They are broadcasted in the 300 kHz radio-navigation band in accordance with ITU-R Recommendations [DIN EN 61108-4]. Even if such systems, also called Ground Based Augmentation Systems (GBAS), increase the accuracy and integrity of GNSS substantially, the performance reached by these systems is not sufficient to meet all International Maritime Organization (IMO) requirements, especially those for critical traffic areas like ports and for e.g. automatic docking manoeuvres [IMO A.915(22)]. In order to support the applicability of satellite navigation in such areas, the German Aerospace Centre (DLR) has started to develop a maritime GBAS that meets all IMO requirements. While the current IALA (International Association of Marine Aids to Navigation and Lighthouse Authorities) GBAS is a Code-based Differential GNSS (C-DGNSS), what means it broadcasts information concerning code corrections, our developments aim for multi-frequency Phase-based Differential GNSS (P-DGNSS). For this purpose DL